Furthermore, in the clinical context of CRC samples lacking MHC-I and mismatch repair mechanisms, abundant Vδ1 and Vδ3 T cells expressing PD-1 and NKRs (particularly NKG2D), which play crucial roles in the efficacy of immune-checkpoint inhibitors, have been observed [1, 27]. This evidence concerns the gene KLRK1 and colorectal carcinoma.